Corrosion-resistant water-based paint and preparation process thereof

Abstract

The invention relates to the technical field of paint, in particular to corrosion-resistant water-based paint and a preparation process thereof. The water-based paint overcomes the problems of poor corrosion resistance and mechanical properties of water-based paint. Graphene oxide is used for modifying waterborne polyurethane, and the concentration of graphene oxide, the concentration of stannous octoate, the prepolymerization temperature, the chain extension temperature and the neutralization temperature are changed; the part ratio of the epoxy resin to the modified waterborne polyurethane and the hard segment content of the modified waterborne polyurethane are changed, so that the mechanical property of the prepared waterborne paint is remarkably improved; by preparing the corrosion inhibitor, the part ratio of sodium oleate to aramid nanofiber, the part ratio of sodium oleate to zeolite particles, the stirring time of the component A and the stirring time of the component B are changed; changing the stirring speed and stirring time of the slurry, the mixture and the water-based paint; the modified graphene oxide is prepared, and the part ratio of quinacridone to the modified graphene oxide is changed, so that the corrosion resistance of the prepared water-based paint is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of paints, and particularly to a corrosion-resistant waterborne paint and a preparation process thereof. Background Art

[0002] The paint industry belongs to modern industry. In traditional paints, organic solvents such as formaldehyde and benzene are usually used as solvents for film-forming substances. Therefore, a large amount of volatile organic compounds will be released during the volatilization process, which will not only cause environmental pollution but also pose great harm to human health. In recent years, with the improvement of global environmental awareness and the restrictions on the emissions of volatile organic compounds (VOCs) by regulations, traditional solvent-based paints have been gradually phased out by the market, and are replaced by more environmentally friendly waterborne paints.

[0003] Waterborne paints use water-based polymers as film-forming substances. Not only are organic solvents not used in the manufacturing process, but also no organic solvents are emitted during the construction process, which fully complies with the internationally popular four E principles (economy, environmental protection, high efficiency, and excellent performance). Waterborne paints have attracted much attention due to their advantages such as low VOCs content, non-toxic and odorless, and easy construction. They can be used on various materials such as woodware, metal, plastic, glass, and building surfaces, showing extremely good development prospects.

[0004] As an environment-friendly coating, waterborne paints have the characteristics of water resistance, abrasion resistance, yellowing resistance, fast drying, and easy use. However, the corrosion resistance and mechanical properties of waterborne paints on the current market still need to be improved.

[0005] Therefore, a corrosion-resistant waterborne paint and a preparation process thereof are proposed. Summary of the Invention

[0006] The object of the present invention is to provide a corrosion-resistant waterborne paint and its preparation process. By using graphene oxide to modify waterborne polyurethane, changing the concentration of graphene oxide, the concentration of stannous octoate, the pre-polymerization temperature, the chain extension temperature, and the neutralization temperature, the molecular weight of the polyurethane emulsion is increased. Moreover, the excellent mechanical properties of graphene oxide and the hydrogen bonds formed by the abundant oxygen-containing functional groups on its surface enhance the intermolecular interaction, and the mechanical properties of the prepared corrosion-resistant waterborne paint are significantly improved; by changing the ratio of epoxy resin to modified waterborne polyurethane and the hard segment content of the modified waterborne polyurethane, the cohesive energy of the hard segment micro-region of the waterborne polyurethane is enhanced, making the polymer have a certain rigidity, and the mechanical properties of the prepared corrosion-resistant waterborne paint are improved; by preparing a corrosion inhibitor and changing the ratio of sodium oleate to aramid nanofibers, the ratio of sodium oleate to zeolite particles, the stirring time of component A, and the stirring time of component B, the corrosion inhibition components can be completely released. When the prepared corrosion inhibitor is applied to the waterborne paint, the corrosion resistance of the paint is significantly improved; by changing the stirring speed and stirring time of the slurry, the mixture, and the waterborne paint, the various components in the waterborne paint can be fully dispersed and dissolved during the preparation process, and the corrosion resistance of the prepared waterborne paint is improved; by preparing modified graphene oxide, changing the type of catalyst, the mass ratio of graphene oxide, catalyst, and melamine, and the heating temperature of the suspension during the preparation process, and changing the ratio of quinacridone to modified graphene oxide, the shielding effect of graphene on corrosion factors can be fully exerted, and the corrosion resistance of the prepared waterborne paint is significantly improved.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] On the one hand, the present invention provides a preparation process of a corrosion-resistant waterborne paint, and the preparation process of the corrosion-resistant waterborne paint is as follows:

[0009] Under stirring conditions, epoxy resin and modified waterborne polyurethane are added to deionized water and mixed evenly to obtain a slurry; the stirring speed is 450 - 550 rpm; the stirring time is 25 - 35 min; zinc phosphate particles and modified graphene oxide are added to the slurry, and stirring is continued at a speed of 300 - 350 rpm for 55 - 65 min to obtain a mixture; an antifoaming agent, a thickening agent, a dispersing agent, and a corrosion inhibitor are added to the mixture, and stirring is carried out at a speed of 500 - 600 rpm for 30 - 40 min to obtain the corrosion-resistant waterborne paint;

[0010] The modified waterborne polyurethane is obtained by graphene oxide through a pre-polymerization reaction, a chain extension reaction, and a neutralization reaction; the pre-polymerization reaction temperature is 70 - 75 °C; the chain extension reaction temperature is 85 - 95 °C; the neutralization reaction temperature is 50 - 60 °C;

[0011] The modified graphene oxide is obtained by reacting the graphene oxide, a catalyst, and melamine in N,N-dimethylformamide; the mass ratio of the graphene oxide, the catalyst, and the melamine is 1:0.5:2.5 - 3.5;

[0012] The corrosion inhibitor includes sodium oleate, aramid nanofibers, and zeolite particles; the ratio of the number of parts of sodium oleate to aramid nanofibers is 1 - 5:1; the ratio of the number of parts of sodium oleate to zeolite particles is 1 - 4:1.2.

[0013] Preferably, the ratio of the number of parts of the epoxy resin to the modified waterborne polyurethane is 1.5 - 2.1:1.2.

[0014] Preferably, the hard segment content of the modified waterborne polyurethane is 35% - 55%.

[0015] Preferably, the dispersant is quinacridone; the ratio of the number of parts of quinacridone to the modified graphene oxide is 1.8:7 - 12.

[0016] Preferably, the preparation process of the modified waterborne polyurethane is as follows: Add the graphene oxide to the deionized water and ultrasonically crush to obtain a suspension; the concentration of the graphene oxide in the suspension is 1.2 - 1.8 wt%; Add isophorone diisocyanate and the suspension to a three-necked flask and stir for 0.8 h to obtain a first mixture; Add PPG-2000 and 1.5 - 2.5 wt% of stannous octoate to the first mixture to obtain a prepolymer; Mix ethylene glycol and acetone evenly and dropwise add them to the prepolymer and react for 1.5 h to obtain a second mixture; Dissolve 2,2-dimethylolpropionic acid in N-methylpyrrolidone to obtain a third mixture; Drop the third mixture into the second mixture to obtain a fourth mixture; Add ammonia water to the fourth mixture for the neutralization reaction, and after reacting for 20 min, cool to room temperature to obtain the modified waterborne polyurethane.

[0017] Preferably, the preparation process of the modified graphene oxide is as follows: Ultrasonically disperse the graphene oxide, the catalyst, and melamine in N,N-dimethylformamide for 1 h to obtain a suspension; Heat the suspension to 80 - 100 °C and stir for 10 h to obtain a brown suspension; Wash the brown suspension three times with N,N-dimethylformamide and boiling water at 100 °C, and then dry at 70 °C for 20 h to obtain the modified graphene oxide.

[0018] Preferably, the catalyst is one of dicyclohexylcarbodiimide, diisopropylcarbodiimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, and N,N-di-tert-butylcarbodiimide.

[0019] Preferably, the graphene oxide is flaky.

[0020] Preferably, the preparation process of the corrosion inhibitor is as follows: Mix 1 / 3 of the total weight portion of the sodium oleate with the aramid nanofibers in the deionized water and stir for 20 - 35 min to obtain Component A; Mix the remaining 2 / 3 of the sodium oleate with the zeolite particles in the deionized water and stir for 15 - 20 h to obtain Component B; Mix Component A and Component B to obtain the corrosion inhibitor.

[0021] On the other hand, the present invention provides a corrosion - resistant water - based paint. The raw materials used for producing the corrosion - resistant water - based paint include epoxy resin, modified water - based polyurethane, corrosion inhibitor, modified graphene oxide, and quinacridone.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. In the present invention, graphene oxide is used to modify water - based polyurethane. Graphene oxide is evenly grafted onto the polyurethane molecules, increasing the molecular weight of the polyurethane emulsion. Moreover, the excellent mechanical properties of graphene oxide and the hydrogen bonds formed by the abundant oxygen - containing functional groups on its surface enhance the intermolecular interaction. By changing the concentration of graphene oxide, the concentration of stannous octoate, the pre - polymerization temperature, the chain - extending temperature, and the neutralization temperature, modified water - based polyurethane is prepared. The corrosion - resistant water - based paint prepared by mixing it with epoxy resin as the matrix has a tensile strength of 1.15 MPa. No cracks, wrinkles, or peeling phenomena are observed in the impact experiment at 50 cm, and the mechanical properties are significantly improved.

[0024] 2. In the present invention, by changing the ratio of the amounts of epoxy resin and modified water - based polyurethane and the hard - segment content of the modified water - based polyurethane, the cohesive energy of the hard - segment microdomains of the water - based polyurethane is enhanced, making the polymer have a certain rigidity. The corrosion - resistant water - based paint prepared has improved mechanical properties, with a tensile strength of 1.37 MPa. No cracks, wrinkles, or peeling phenomena are observed in the impact experiment at 50 cm.

[0025] 3. In the present invention, by preparing a corrosion inhibitor and changing the ratio of the amounts of sodium oleate and aramid nanofibers, the ratio of the amounts of sodium oleate and zeolite particles, the stirring time of Component A, and the stirring time of Component B, the sodium oleate adsorbed on the zeolite particles promotes the connection between the aramid nanofibers and the zeolite particles, thereby fully releasing the sodium ions inside the zeolite particles, increasing the pH value of the solution, and completely releasing the corrosion - inhibiting components. When the prepared corrosion inhibitor is applied to the water - based paint, the corrosion - resistant performance of the paint is significantly improved. There is no abnormality after soaking in a 50 g / L sulfuric acid solution for 192 h, no abnormality after soaking in a 50 g / L sodium hydroxide solution for 168 h, and no blistering, peeling, rusting, or cracking phenomena occur in the salt - spray resistance test for 3620 h.

[0026] 4. By changing the stirring speed and time of the slurry, mixture, and water-based paint, the present invention can fully disperse and dissolve various components in the water-based paint during the preparation process. The prepared water-based paint has improved corrosion resistance, showing no abnormalities after being immersed in a 50 g / L sulfuric acid solution for 192 h, no abnormalities after being immersed in a 50 g / L sodium hydroxide solution for 168 h, and no phenomena of blistering, peeling, rusting, or cracking within 3620 h during the salt spray resistance performance test.

[0027] 5. By preparing modified graphene oxide and changing the types of catalysts, the mass ratios of graphene oxide, catalyst, and melamine, and the heating temperature of the suspension during the preparation process, the present invention can improve the dispersibility of the modified graphene oxide and extend the diffusion path of the corrosive medium to the substrate, thereby enhancing the anti-corrosion performance of the composite material. By changing the ratio of quinacridone to modified graphene oxide, quinacridone and modified graphene oxide can form π-π bonds, improving their dispersibility in the water-based paint. Moreover, quinacridone adsorbs on the surface of graphene to form a flaky crystal structure, which can fully exert the shielding effect of graphene on corrosion factors. The prepared water-based paint has significantly improved corrosion resistance, showing no abnormalities after being immersed in a 50 g / L sulfuric acid solution for 192 h, no abnormalities after being immersed in a 50 g / L sodium hydroxide solution for 168 h, and no phenomena of blistering, peeling, rusting, or cracking within 3691 h during the salt spray resistance performance test. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a graph showing the mechanical property test results of Examples 17, 19 - 22 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] Please refer to Figure 1 , the present invention provides a corrosion-resistant water-based paint and its preparation process, and the technical solutions are as follows:

[0031] The substances involved in the present invention are as follows:

[0032] Epoxy resin CAS: 24969-06-0; Zinc phosphate CAS: 7779-90-0; Sodium oleate CAS: 143-19-1; Zeolite CAS: 1318-02-1; Quinacridone CAS: 1047-16-1; Isophorone diisocyanate CAS: 4098-71-9; Stannous octoate CAS: 301-10-0; Ethylene glycol CAS: 107-21-1; Acetone CAS: 67-64-1; 2,2-Dimethylolpropionic acid CAS: 4767-03-7; N-Methylpyrrolidone CAS: 872-50-4; Ammonia water CAS: 1336-21-6; Polydimethylsiloxane CAS: 9016-00-6; Polyacrylamide CAS: 9003-05-8; Melamine CAS: 108-78-1; N,N-Dimethylformamide CAS: 68-12-2; Dicyclohexylcarbodiimide CAS: 538-75-0; Diisopropylcarbodiimide CAS: 693-13-0; 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide CAS: 1892-57-5; N,N-Di-tert-butylcarbodiimide CAS: 691-24-7; Graphene oxide was purchased from Beijing Huawei Ruike Chemical Technology Co., Ltd.; Aramid nanofibers were purchased from Beijing Tongtai Jiahua Technology Co., Ltd.; PPG-2000 was purchased from Shanghai Kaibite Chemical Co., Ltd.

[0033] It should be noted that the parts in the present invention are all parts by weight.

[0034] Example 1

[0035] Preparation of modified aqueous polyurethane: Add 10 parts of graphene oxide to deionized water and ultrasonically crush to obtain a suspension; the concentration of graphene oxide in the suspension is 1.2 wt%; Add 20 parts of isophorone diisocyanate and the suspension to a three-necked flask, and stir at 70 °C for 0.8 h to obtain a mixture I; Add 1.0 wt% of PPG-2000 and 1.5 wt% of stannous octoate to the mixture I to obtain a prepolymer; Mix ethylene glycol and acetone evenly in a ratio of 1:1.5 by parts and drop them into the prepolymer, and react at 85 °C for 1.5 h to obtain a mixture II; Dissolve 5 parts of 2,2-dimethylolpropionic acid in 8 parts of N-methylpyrrolidone to obtain a mixture III; Drop the mixture III into the mixture II to obtain a mixture IV; Add 3 parts of ammonia water to the mixture IV for neutralization reaction, react at 50 °C for 20 min and then cool to room temperature to obtain modified aqueous polyurethane.

[0036] Preparation of corrosion inhibitor: Mix 6 parts of sodium oleate with aramid nanofibers in 25 parts of deionized water and stir for 20 min to obtain Component A; mix 12 parts of sodium oleate with zeolite particles in 35 parts of deionized water and stir for 15 h to obtain Component B; mix Component A and Component B to obtain the corrosion inhibitor; the ratio of the number of parts of sodium oleate to aramid nanofibers is 1:1; the ratio of the number of parts of sodium oleate to zeolite particles is 1:1.2.

[0037] Preparation of modified graphene oxide: Ultrasonically disperse 120 mg of graphene oxide, the catalyst dicyclohexylcarbodiimide, and melamine in 100 ml of N,N-dimethylformamide for 1 h to obtain a suspension; heat the suspension to 80 °C and stir for 10 h to obtain a brown suspension; wash the brown suspension three times with N,N-dimethylformamide and boiling water at 100 °C, and then dry it at 70 °C for 20 h to obtain the modified graphene oxide; the mass ratio of graphene oxide, the catalyst, and melamine is 1:0.5:2.5; the graphene oxide is flaky.

[0038] Preparation of corrosion-resistant waterborne paint: Under stirring conditions, add 70 parts of epoxy resin and modified waterborne polyurethane to deionized water and mix evenly to obtain a slurry; the stirring speed is 450 rpm; the stirring time is 25 min; add 5 parts of zinc phosphate particles and 7 parts of modified graphene oxide to the slurry, and continue to stir at a speed of 300 rpm for 55 min to obtain a mixture; add 1.5 parts of the defoamer polydimethylsiloxane, 1.2 parts of the thickener polyacrylamide, the dispersant quinacridone, and 5 parts of the corrosion inhibitor to the mixture, and stir at a speed of 500 rpm for 30 min to obtain the corrosion-resistant waterborne paint; the ratio of the number of parts of epoxy resin to modified waterborne polyurethane is 1.5:1.2; the hard segment content of the modified waterborne polyurethane is 35%; the ratio of the number of parts of quinacridone to modified graphene oxide is 1.8:7.

[0039] Examples 2 - 14

[0040] Refer to the preparation method and parameter conditions of Example 1, and the specific differences are shown in Table 1.

[0041] Table 1 Specific preparation parameters of Examples 2 - 14

[0042] Example Concentration of graphene oxide / wt% Concentration of stannous octoate / wt% Prepolymerization temperature / °C Chain extension temperature / °C Neutralization temperature / °C Example 2 1.4 1.5 70 85 50 Example 3 1.6 1.5 70 85 50 Example 4 1.8 1.5 70 85 50 Example 5 1.4 1.8 70 85 50 Example 6 1.4 2.2 70 85 50 Example 7 1.4 2.5 70 85 50 Example 8 1.4 1.8 72 85 50 Example 9 1.4 1.8 75 85 50 Example 10 1.4 1.8 72 88 50 Example 11 1.4 1.8 72 90 50 Example 12 1.4 1.8 72 95 50 Example 13 1.4 1.8 72 90 54 Example 14 1.4 1.8 72 90 60

[0043] Comparative Example 1

[0044] Prepare the corrosion-resistant waterborne paint according to the method of Example 1, but the difference is that the waterborne polyurethane is not modified.

[0045] Example 15 Mechanical property test

[0046] Tensile strength test: The tensile machine was used to test the film layer specimens. The specimens were dumbbell-shaped splines. They were placed at room temperature for 24 h to eliminate internal stress, and the tensile rate was 1 mm / min;

[0047] Impact strength: According to the standard in GB / T 1732-2020 "Determination of impact resistance of paint films", the impact strength of the waterborne paint was tested; The obtained results are shown in Table 2.

[0048] Table 2 Mechanical property tests of Examples 1-14 and Comparative Example 1

[0049] Example Tensile strength / MPa Impact strength / cm Example 1 0.87 45 Example 2 0.89 50 Example 3 0.91 45 Example 4 0.88 45 Example 5 0.95 50 Example 6 0.94 50 Example 7 0.91 45 Example 8 0.98 50 Example 9 0.97 50 Example 10 1.04 50 Example 11 1.15 50 Example 12 0.86 50 Example 13 1.28 50 Example 14 1.02 50 Comparative Example 1 0.43 35

[0050] As can be seen from Table 2, in Examples 1-4, when the concentration of graphene oxide is too low, its distribution in waterborne polyurethane is relatively sparse, and the interaction between the two weakens, thus affecting the mechanical properties of the material; when the concentration of graphene oxide is too high, the graphene sheets are prone to agglomeration, forming larger particles, which act as stress concentration points in the waterborne polyurethane matrix, resulting in a decrease in the mechanical properties of the material. In Example 2, the best effect is achieved when the concentration of graphene oxide is 1.4 wt%. The main role of stannous octoate in the synthesis of modified waterborne polyurethane is to promote the reaction between isocyanate groups and hydroxyl groups, that is, to promote the growth of polymer chains. In Examples 2, 5-7, when the concentration of stannous octoate is too low, its catalytic efficiency is low, resulting in insufficient degree of polymerization, thus affecting the mechanical properties of waterborne polyurethane; when the concentration of stannous octoate is too high, it will cause premature gelation of waterborne polyurethane during preparation, which will affect the cell structure of polyurethane, making most of the cells closed cells, limiting the deformation ability of the foam body when subjected to impact, resulting in weakened energy absorption and dispersion effects, and decreased impact resistance. In Example 5, the best mechanical properties of waterborne polyurethane are obtained when the concentration of stannous octoate is 1.8 wt%. In Examples 5, 8-9, if the temperature of the prepolymerization reaction is too high, it will lead to uneven molecular weight distribution of the prepolymer, affecting the mechanical properties of waterborne polyurethane, and at high temperatures, the raw materials may undergo thermal degradation, resulting in a decrease in the quality of the prepolymer; if the temperature of the prepolymerization reaction is too low, stress concentration points will be generated, reducing the mechanical properties of waterborne polyurethane. In Example 8, the best effect of the prepolymerization reaction is achieved at 72 °C. In Examples 8, 10-12, if the chain extension reaction temperature is too high, it will lead to uneven distribution of chain segment lengths, affecting the crosslinking degree and molecular weight distribution of waterborne polyurethane, and at high temperatures, the polyurethane chain segments will undergo thermal degradation, resulting in a decrease in mechanical properties; if the chain extension reaction temperature is too low, the chain extension reaction will be incomplete, leaving unreacted functional groups, resulting in insufficient chain segment growth, which will also have a negative impact on the mechanical properties of waterborne polyurethane. In Example 11, the best chain extension reaction temperature is 90 °C. In Examples 11, 13-14, if the neutralization reaction temperature is too high, it may lead to too strong ionic crosslinking, making the molecular chain spacing of waterborne polyurethane too large, thus reducing its mechanical properties; if the neutralization reaction temperature is too low, it may lead to incomplete neutralization, leaving unreacted carboxyl groups or amine groups and other functional groups. In addition, the stability of the polyurethane emulsion will also decrease, thus reducing the mechanical properties of waterborne polyurethane; in Example 13, when the concentration of graphene oxide is 1.4 wt%, the concentration of stannous octoate is 1.8 wt%, the prepolymerization reaction is carried out at 72 °C, the chain extension reaction is carried out at 90 °C, and the neutralization reaction is carried out at 54 °C, the prepared modified waterborne polyurethane has the best mechanical properties. When it is mixed with epoxy resin as the matrix, the tensile strength of the corrosion-resistant waterborne paint is 1.15 MPa, and no cracks, wrinkles or peeling phenomena are observed in the impact experiment at 50 cm.In Comparative Example 1, the unmodified aqueous polyurethane was applied to the aqueous paint, and its mechanical properties were significantly reduced.

[0051] Example 16

[0052] Prepare modified aqueous polyurethane: Add 10 parts of graphene oxide to deionized water and ultrasonically crush to obtain a suspension; the concentration of graphene oxide in the suspension is 1.4 wt%; add 20 parts of isophorone diisocyanate and the suspension to a three-necked flask and stir at 72 °C for 0.8 h to obtain a first mixed solution; add 1.0 wt% of PPG-2000 and 1.8 wt% of stannous octoate to the first mixed solution to obtain a prepolymer; mix ethylene glycol and acetone evenly at a ratio of 1:1.5 by parts and then dropwise add them to the prepolymer, and react at 90 °C for 1.5 h to obtain a second mixture; dissolve 5 parts of 2,2-dimethylolpropionic acid in 8 parts of N-methylpyrrolidone to obtain a third mixture; drop the third mixture into the second mixture to obtain a fourth mixture; add 3 parts of ammonia water to the fourth mixture for neutralization reaction, react at 54 °C for 20 min and then cool to room temperature to obtain the modified aqueous polyurethane.

[0053] Prepare a corrosion inhibitor: Mix 6 parts of sodium oleate and aramid nanofibers in 25 parts of deionized water and stir for 20 min to obtain Component A; mix 12 parts of sodium oleate and zeolite particles in 35 parts of deionized water and stir for 15 h to obtain Component B; mix Component A and Component B to obtain the corrosion inhibitor; the ratio of the parts of sodium oleate to aramid nanofibers is 1:1; the weight ratio of sodium oleate to zeolite particles is 1:1.2.

[0054] Prepare modified graphene oxide: Ultrasonically disperse 120 mg of graphene oxide, the catalyst dicyclohexylcarbodiimide and melamine in 100 ml of N,N-dimethylformamide for 1 h to obtain a suspension; heat the suspension to 80 °C and stir for 10 h to obtain a brown suspension; wash the brown suspension three times with N,N-dimethylformamide and boiling water at 100 °C, and then dry at 70 °C for 20 h to obtain the modified graphene oxide; the mass ratio of graphene oxide, the catalyst and melamine is 1:0.5:2.5; the graphene oxide is flaky.

[0055] Preparation of corrosion-resistant waterborne paint: 70 parts of epoxy resin and modified waterborne polyurethane are added to deionized water under stirring conditions and mixed evenly to obtain a slurry; the stirring speed is 450 rpm; the stirring time is 25 min; 5 parts of zinc phosphate particles and 7 parts of modified graphene oxide are added to the slurry, and stirring is continued at a speed of 300 rpm for 55 min to obtain a mixture; 1.5 parts of defoamer polydimethylsiloxane, 1.2 parts of thickener polyacrylamide, dispersant quinacridone and 5 parts of corrosion inhibitor are added to the mixture, and stirring is carried out at a speed of 500 rpm for 30 min to obtain the corrosion-resistant waterborne paint; the ratio of the parts of epoxy resin to modified waterborne polyurethane is 1.7:1.2; the hard segment content of the modified waterborne polyurethane is 35%; the ratio of the parts of quinacridone to modified graphene oxide is 1.8:7.

[0056] Examples 17 - 22

[0057] Referring to the preparation method and parameter conditions of Example 16, the specific differences are shown in Table 3.

[0058] Example 23 Mechanical Property Test

[0059] Tensile strength test: The film layer specimen is tested by a tensile machine. The specimen is a dumbbell-shaped spline, and internal stress is eliminated by placing it at room temperature for 24 h. The tensile rate is 1 mm / min.

[0060] Impact resistance: According to the standard in GB / T1732 - 2020 "Determination of Impact Resistance of Paint Films", the impact resistance of the waterborne paint is tested; the obtained results are shown in Table 3 and Figure 1 as shown.

[0061] Table 3 Mechanical Property Tests of Examples 16 - 22

[0062] Example Ratio of epoxy resin to modified waterborne polyurethane Hard segment content of modified waterborne polyurethane / % Tensile strength / MPa Impact strength / cm Example 16 1.7：1.2 35 1.18 50 Example 17 1.8：1.2 35 1.23 50 Example 18 2.1：1.2 35 1.20 45 Example 19 1.8：1.2 40 1.29 50 Example 20 1.8：1.2 45 1.37 50 Example 21 1.8：1.2 50 1.32 50 Example 22 1.8：1.2 55 1.26 45

[0063] As can be seen from Table 3, in Example 18, the content of epoxy resin is too high. Since epoxy resin itself has high rigidity and hardness, it will cause an increase in the overall rigidity of the material and a relative decrease in toughness. Therefore, the brittleness of the material increases and the impact resistance decreases. In Examples 11 and 16, when the content of modified waterborne polyurethane is too high, due to the good flexibility of the polyurethane molecular chain, it will cause an increase in the overall toughness of the material and a relative decrease in rigidity, resulting in a decrease in the tensile strength of the material. In Example 17, when the ratio of the parts of epoxy resin to modified waterborne polyurethane is 1.8:1.2, the comprehensive mechanical properties are the best. The hard segment microregions of waterborne polyurethane have strong polarity and are prone to form hydrogen bonds, enhancing the cohesive energy of this microregion and making the polymer have a certain rigidity, thus endowing polyurethane with good tensile strength and impact resistance. From Table 3 and Figure 1It can be seen that in Examples 17, 19 - 22, too low a hard segment content in the modified aqueous polyurethane will lead to insufficient hardness and rigidity of the aqueous polyurethane, making the material too soft and prone to deformation; in addition, the hard segment also affects the heat resistance of the polyurethane. Too low a hard segment content will cause the heat resistance of the prepared corrosion - resistant aqueous paint to decline, and it is prone to deformation and degradation at high temperatures, thus greatly reducing the mechanical properties; as the hard segment content increases, the cohesion and structural stability of the material will be enhanced, and the tensile strength of the aqueous polyurethane will increase accordingly. When the hard segment content is 45%, the tensile strength reaches the maximum; however, in Examples 21 - 22, too high a hard segment content will lead to poor compatibility between the hard and soft segments, which instead affects the mechanical properties of the material. In Example 20, when the hard segment content of the modified aqueous polyurethane is 45% and the weight ratio of epoxy resin to modified aqueous polyurethane is 1.8:1.2, the prepared corrosion - resistant aqueous paint has the best mechanical properties, with a tensile strength of 1.37 MPa, and no cracks, wrinkles or peeling phenomena are observed in the impact experiment at 50 cm.

[0064] Example 24

[0065] Prepare the modified aqueous polyurethane according to the method of Example 16 above.

[0066] Prepare the corrosion inhibitor: Mix 6 parts of sodium oleate with aramid nanofibers in 25 parts of deionized water and stir for 20 min to obtain Component A; mix 12 parts of sodium oleate with zeolite particles in 35 parts of deionized water and stir for 15 h to obtain Component B; mix Component A and Component B to obtain the corrosion inhibitor; the ratio of the number of parts of sodium oleate to aramid nanofibers is 2:1; the ratio of the number of parts of sodium oleate to zeolite particles is 1:1.2.

[0067] Prepare the modified graphene oxide: Ultrasonically disperse 120 mg of graphene oxide, the catalyst dicyclohexylcarbodiimide and melamine in 100 ml of N, N - dimethylformamide for 1 h to obtain a suspension; heat the suspension to 80 °C and stir for 10 h to obtain a brown suspension; wash the brown suspension three times with N, N - dimethylformamide and boiling water at 100 °C, and then dry it at 70 °C for 20 h to obtain the modified graphene oxide; the mass ratio of graphene oxide, catalyst and melamine is 1:0.5:2.5; the graphene oxide is flaky.

[0068] Preparation of corrosion-resistant waterborne paint: 70 parts of epoxy resin and modified waterborne polyurethane are added to deionized water under stirring conditions and mixed evenly to obtain a slurry; the stirring speed is 450 rpm; the stirring time is 25 min; 5 parts of zinc phosphate particles and 7 parts of modified graphene oxide are added to the slurry, and stirring is continued at a speed of 300 rpm for 55 min to obtain a mixture; 1.5 parts of defoamer polydimethylsiloxane, 1.2 parts of thickener polyacrylamide, dispersant quinacridone and 5 parts of corrosion inhibitor are added to the mixture, and stirring is carried out at a speed of 500 rpm for 30 min to obtain the corrosion-resistant waterborne paint; the ratio of the parts of epoxy resin to modified waterborne polyurethane is 1.8:1.2; the hard segment content of the modified waterborne polyurethane is 45%; the ratio of the parts of quinacridone to modified graphene oxide is 1.8:7.

[0069] Examples 25 - 35

[0070] Referring to the preparation method and parameter conditions of Example 24, the specific differences are shown in Table 4.

[0071] Table 4 Specific preparation parameters of Examples 25 - 35

[0072] Example Ratio of sodium oleate to aramid nanofibers Ratio of sodium oleate to zeolite particles Stirring time of Component A / min Stirring time of Component B / h Example 25 3：1 1：1.2 20 15 Example 26 4：1 1：1.2 20 15 Example 27 5：1 1：1.2 20 15 Example 28 3：1 2.5：1.2 20 15 Example 29 3：1 3.5：1.2 20 15 Example 30 3：1 4：1.2 20 15 Example 31 3：1 3.5：1.2 25 15 Example 32 3：1 3.5：1.2 30 15 Example 33 3：1 3.5：1.2 35 15 Example 34 3：1 3.5：1.2 30 18 Example 35 3：1 3.5：1.2 30 20

[0073] Example 36 Corrosion resistance test

[0074] Acid resistance test: According to Method A in the standard GB / T9274 - 1988, the acid resistance of the waterborne paint in a 50 g / L sulfuric acid solution for 192 h is tested;

[0075] Alkali resistance test: According to Method A in the standard GB / T9274 - 1988, the alkali resistance of the waterborne paint in a 50 g / L sodium hydroxide solution for 168 h is tested;

[0076] Salt spray resistance: According to the standard GB / T1771 - 2007, the salt spray resistance of the waterborne paint is tested, the coating thickness is 100 ± 10 μm, and the time when phenomena such as blistering, peeling, rusting, and cracking occur is tested; the obtained results are shown in Table 5.

[0077] Table 5 Corrosion resistance test of Examples 20, 24 - 35

[0078] Example Acid resistance Alkali resistance Salt spray resistance / h Example 20 A few rust spots A few rust spots 3544 Example 24 A few rust spots A few rust spots 3552 Example 25 No abnormality No abnormality 3560 Example 26 No abnormality No abnormality 3552 Example 27 No abnormality No abnormality 3543 Example 28 A few rust spots A few rust spots 3561 Example 29 No abnormality No abnormality 3570 Example 30 A few rust spots A few rust spots 3560 Example 31 No abnormality No abnormality 3575 Example 32 No abnormality No abnormality 3600 Example 33 No abnormality No abnormality 3583 Example 34 No abnormality No abnormality 3620 Example 35 No abnormality No abnormality 3619

[0079] As can be seen from Table 5, in Examples 20, 24 - 27, when changing the ratio of the number of parts of sodium oleate to aramid nanofibers, if the proportion of sodium oleate is too low, it cannot fully wrap the modified aramid nanofibers, resulting in a decrease in the corrosion resistance of the corrosion inhibitor; if the proportion of sodium oleate is too high, it will lead to an excessive amount of oily components in the corrosion inhibitor, while the enhancement or modification effect of aramid nanofibers is relatively weakened, and too much sodium oleate will affect the dispersion of aramid nanofibers in deionized water, ultimately affecting the uniformity and stability of the corrosion inhibitor. In Example 25, when the ratio of the number of parts of sodium oleate to aramid nanofibers is 3:1, the corrosion inhibitor can play its role fully. In Examples 25, 28 - 30, when changing the ratio of the number of parts of sodium oleate to zeolite particles, if the proportion of sodium oleate is too low, it cannot promote the connection between zeolite particles and aramid nanofibers; if the proportion of sodium oleate is too high, it will cause excessive coverage of sodium oleate on zeolite particles, hindering the release of sodium ions in zeolite particles and the increase in pH, making the corrosion inhibition components unable to be released effectively, and the corrosion resistance of the prepared waterborne paint is poor. In Example 29, when the ratio of the number of parts of sodium oleate to zeolite particles is 3.5:1.2, the corrosion resistance effect is the best. In Examples 29, 31 - 33, if the stirring time of Component A is too short, aramid nanofibers will agglomerate together to form larger particles, reducing the effective surface area of the corrosion inhibitor, thus affecting its ability to inhibit corrosion; if the stirring time is too long, sodium oleate or aramid nanofibers will undergo degradation or chemical changes, which will have a negative impact on the performance of the corrosion inhibitor. In Example 32, the most suitable stirring time of Component A is 30 min. In Examples 32, 34 - 35, if the stirring time of Component B is too short, sodium oleate cannot fully cover the surface of zeolite particles, resulting in poor dispersion of zeolite particles in deionized water, thus affecting the uniformity and stability of the corrosion inhibitor; as the stirring time increases, it helps sodium oleate to cover the surface of zeolite particles more evenly, and zeolite particles can be fully dispersed in deionized water, thereby enhancing the adsorption ability and ion exchange performance of zeolite particles and improving the corrosion resistance of the corrosion inhibitor; however, too long a stirring time does not further improve the performance of the corrosion inhibitor. In Example 34, when the ratio of the number of parts of sodium oleate to aramid nanofibers is 3:1, the ratio of the number of parts of sodium oleate to zeolite particles is 3.5:1.2, the stirring time of Component A is 30 min, and the stirring time of Component B is 18 h, the prepared corrosion inhibitor is applied to waterborne paint, and the corrosion resistance of the paint is the best. There is no abnormality after soaking in 50 g / L sulfuric acid solution for 192 h, no abnormality after soaking in 50 g / L sodium hydroxide solution for 168 h, and no phenomena of blistering, peeling, rusting, and cracking occur in the salt spray resistance test for 3620 h.

[0080] Example 37

[0081] Prepare modified waterborne polyurethane according to the method of Example 16 above.

[0082] Preparation of corrosion inhibitor: Mix 6 parts of sodium oleate with aramid nanofibers in 25 parts of deionized water and stir for 30 min to obtain Component A; mix 12 parts of sodium oleate with zeolite particles in 35 parts of deionized water and stir for 18 h to obtain Component B; mix Component A and Component B to obtain the corrosion inhibitor; the ratio of the parts of sodium oleate to aramid nanofibers is 3:1; the ratio of the parts of sodium oleate to zeolite particles is 3.5:1.2.

[0083] Preparation of modified graphene oxide: Ultrasonically disperse 120 mg of graphene oxide, the catalyst dicyclohexylcarbodiimide, and melamine in 100 ml of N,N-dimethylformamide for 1 h to obtain a suspension; heat the suspension to 80 °C and stir for 10 h to obtain a brown suspension; wash the brown suspension three times with N,N-dimethylformamide and boiling water at 100 °C, and then dry it at 70 °C for 20 h to obtain the modified graphene oxide; the mass ratio of graphene oxide, the catalyst, and melamine is 1:0.5:2.5; the graphene oxide is flaky.

[0084] Preparation of corrosion-resistant waterborne paint: Under stirring conditions, add 70 parts of epoxy resin and modified waterborne polyurethane to deionized water and mix evenly to obtain a slurry; the stirring speed is 480 rpm; the stirring time is 25 min; add 5 parts of zinc phosphate particles and 7 parts of modified graphene oxide to the slurry, and continue to stir at a speed of 300 rpm for 55 min to obtain a mixture; add 1.5 parts of the defoamer polydimethylsiloxane, 1.2 parts of the thickener polyacrylamide, the dispersant quinacridone, and 5 parts of the corrosion inhibitor to the mixture, and stir at a speed of 500 rpm for 30 min to obtain the corrosion-resistant waterborne paint; the ratio of the parts of epoxy resin to modified waterborne polyurethane is 1.8:1.2; the hard segment content of the modified waterborne polyurethane is 45%; the ratio of the parts of quinacridone to modified graphene oxide is 1.8:7.

[0085] Examples 38 - 53

[0086] Refer to the preparation method and parameter conditions of Example 37, and the specific differences are shown in Table 6.

[0087] Table 6 Specific preparation parameters of Examples 38 - 53

[0088]

[0089] Example 54 Corrosion resistance test

[0090] Acid resistance test: Test the acid resistance of the waterborne paint in a 50 g / L sulfuric acid solution for 192 h according to Method A in the standard GB / T9274 - 1988.

[0091] Alkali resistance test: According to the method A in the standard GB / T9274-1988, test the alkali resistance of the waterborne paint in 50g / L sodium hydroxide solution for 168h;

[0092] Salt spray resistance: According to the standard GB / T1771-2007, test the salt spray resistance of the waterborne paint. The coating thickness is 100±10μm, and test the time when blistering, peeling, rusting, and cracking occur; The obtained results are shown in Table 7.

[0093] Table 7 Corrosion resistance test of Examples 34, 37 - 53

[0094] Example Acid resistance Alkali resistance Salt spray resistance / h Example 34 No abnormality No abnormality 3620 Example 37 No abnormality No abnormality 3623 Example 38 No abnormality No abnormality 3627 Example 39 No abnormality No abnormality 3633 Example 40 No abnormality No abnormality 3628 Example 41 No abnormality No abnormality 3635 Example 42 No abnormality No abnormality 3640 Example 43 No abnormality No abnormality 3636 Example 44 No abnormality No abnormality 3643 Example 45 No abnormality No abnormality 3639 Example 46 A few rust spots A few rust spots 3633 Example 47 No abnormality No abnormality 3648 Example 48 No abnormality No abnormality 3645 Example 49 No abnormality No abnormality 3650 Example 50 No abnormality No abnormality 3646 Example 51 A few rust spots A few rust spots 3638 Example 52 No abnormality No abnormality 3654 Example 53 No abnormality No abnormality 3650

[0095] As can be seen from Table 7, in Examples 34, 37 - 43, if the stirring speed of the slurry is too high or too low, the epoxy resin and the modified waterborne polyurethane particles will be unevenly dispersed, resulting in local agglomeration, which will affect the uniformity and stability of the slurry, thus affecting the effect of adding subsequent components and the corrosion resistance of the waterborne paint. If the stirring time is too short, the epoxy resin and the modified waterborne polyurethane cannot be fully dissolved and dispersed in deionized water; if the stirring time is too long, the particles in the slurry will be over-dispersed, resulting in the loss of dispersion stability of the slurry and the appearance of aggregation and precipitation phenomena. In Example 42, it is most suitable to stir at 520 rmp for 31 min. In Examples 42, 44 - 48, if the stirring speed of the mixture is too high, the zinc phosphate particles and graphene oxide will be unevenly distributed in the slurry; if the stirring speed of the mixture is too low, the particles in the slurry cannot be fully dispersed; both will lead to a decrease in the corrosion resistance of the waterborne paint. If the stirring time is too long, the zinc phosphate particles and graphene oxide will be over-dispersed in the slurry, even damaging their structure and affecting the corrosion resistance of the paint; if the stirring time is too short, the zinc phosphate particles and graphene oxide may not be fully incorporated into the slurry, resulting in a decrease in the corrosion resistance of the paint. In Examples 47, 49 - 53, if the stirring speed of the waterborne paint is too high, there will be a phenomenon of too high or too low local concentration of the additive, affecting the corrosion resistance and stability of the paint; if the stirring speed is too low, the additive cannot be fully dispersed and dissolved, resulting in the incomplete exertion of its function, and the corrosion resistance of the waterborne paint will also decrease. If the stirring time is too long, the paint will lose its dispersion stability; if the stirring time is too short, the additive cannot be fully incorporated into the paint, both of which will have a negative impact on the corrosion resistance of the waterborne paint. In Example 52, when the slurry is stirred at 520 rmp for 31 min, the mixture is stirred at 315 rmp for 60 min, and the waterborne paint is stirred at 540 rmp for 35 min, the finally obtained corrosion-resistant waterborne paint has no abnormality after being immersed in a 50 g / L sulfuric acid solution for 192 h, no abnormality after being immersed in a 50 g / L sodium hydroxide solution for 168 h, and no blistering, peeling, rusting, or cracking phenomena occur in the salt spray resistance test for 3620 h, and the corrosion resistance is the best.

[0096] Example 55

[0097] Prepare the modified waterborne polyurethane and the corrosion inhibitor according to the method of Example 37 above.

[0098] Preparation of modified graphene oxide: 120 mg of graphene oxide, the catalyst N,N'-dicyclohexylcarbodiimide, and melamine were ultrasonically dispersed in 100 ml of N,N-dimethylformamide for 1 h to obtain a suspension; the suspension was heated to 80 °C and stirred for 10 h to obtain a brown suspension; the brown suspension was washed three times with N,N-dimethylformamide and boiling water at 100 °C, and then dried at 70 °C for 20 h to obtain the modified graphene oxide; the mass ratio of graphene oxide, the catalyst, and melamine was 1:0.5:2.5; the graphene oxide was flaky.

[0099] Preparation of corrosion-resistant waterborne paint: 70 parts of epoxy resin and modified waterborne polyurethane were added to deionized water under stirring conditions and mixed evenly to obtain a slurry; the stirring speed was 520 rpm; the stirring time was 31 min; 5 parts of zinc phosphate particles and 7 parts of modified graphene oxide were added to the slurry, and the mixture was continuously stirred at a speed of 315 rpm for 60 min to obtain a mixture; 1.5 parts of the defoaming agent polydimethylsiloxane, 1.2 parts of the thickening agent polyacrylamide, the dispersant quinacridone, and 5 parts of the corrosion inhibitor were added to the mixture, and the mixture was stirred at a speed of 540 rpm for 35 min to obtain the corrosion-resistant waterborne paint; the ratio of the parts of epoxy resin to modified waterborne polyurethane was 1.8:1.2; the hard segment content of the modified waterborne polyurethane was 45%; the ratio of the parts of quinacridone to modified graphene oxide was 1.8:7.

[0100] Examples 56 - 65

[0101] Referring to the preparation method and parameter conditions of Example 55, the specific differences are shown in Table 8.

[0102] Table 8 Specific preparation parameters of Examples 56 - 65

[0103] Example Type of catalyst Ratio of graphene oxide, catalyst and melamine Heating temperature of suspension / °C Ratio of quinacridone to modified graphene oxide Example 56 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide 1：0.5：2.5 80 1.8：7 Example 57 N,N-Di-tert-butylcarbodiimide 1：0.5：2.5 80 1.8：7 Example 58 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide 1：0.5：2.8 80 1.8：7 Example 59 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide 1：0.5：3.1 80 1.8：7 Example 60 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide 1：0.5：3.5 80 1.8：7 Example 61 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide 1：0.5：2.8 85 1.8：7 Example 62 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide 1：0.5：2.8 90 1.8：7 Example 63 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide 1：0.5：2.8 100 1.8：7 Example 64 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide 1：0.5：2.8 90 1.8：9 Example 65 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide 1：0.5：2.8 90 1.8：12

[0104] Comparative Example 2

[0105] The corrosion-resistant waterborne paint was prepared according to the method of Example 1, but the difference was that the graphene oxide was not modified.

[0106] Example 66 Corrosion resistance test

[0107] Acid resistance test: According to Method A in the standard GB / T9274 - 1988, the acid resistance of the waterborne paint in a 50 g / L sulfuric acid solution at 192 h was tested.

[0108] Alkali resistance test: According to Method A in the standard GB / T9274 - 1988, the alkali resistance of the waterborne paint in a 50 g / L sodium hydroxide solution at 168 h was tested.

[0109] Salt spray resistance: The salt spray resistance of the water-based paint was tested according to the standard of GB / T 1771-2007. The coating thickness was 100 ± 10 μm, and the time when blistering, peeling, rusting, and cracking occurred was tested. The results are shown in Table 9.

[0110] Table 9 Corrosion resistance test of Examples 52, 55-65, and Comparative Example 2

[0111] Example Acid resistance Alkali resistance Salt spray resistance / h Example 52 No abnormality No abnormality 3654 Example 55 No abnormality No abnormality 3624 Example 56 No abnormality No abnormality 3670 Example 57 A small amount of rust spots A small amount of rust spots 3612 Example 58 No abnormality No abnormality 3675 Example 59 No abnormality No abnormality 3670 Example 60 A small amount of rust spots A small amount of rust spots 3658 Example 61 No abnormality No abnormality 3678 Example 62 No abnormality No abnormality 3687 Example 63 No abnormality No abnormality 3682 Example 64 No abnormality No abnormality 3691 Example 65 No abnormality No abnormality 3684 Comparative Example 2 Obvious rust spots Obvious rust spots 3018

[0112] As can be seen from Table 9, in Examples 52, 55 - 57, when the catalyst type was changed and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide was used as the catalyst, the urea formed in the reaction was water-soluble and easily separated and removed, thus simplifying the post-treatment and purification processes of the reaction. Moreover, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide had good stability and reactivity, and the modified graphene prepared was the most stable, with the best corrosion resistance when applied to waterborne paints. In Examples 56, 58 - 60, when the mass ratios of graphene oxide, catalyst, and melamine were changed, if the proportion of melamine was too high, it might cause self-crosslinking of its chains, thereby inducing precipitation of graphene oxide, destroying the dispersibility of graphene oxide in the solution, and further affecting the structural uniformity and integrity of the modified graphene oxide and its corrosion resistance. In Example 58, the material prepared with a mass ratio of graphene oxide, catalyst, and melamine of 1:0.5:2.8 had the best corrosion resistance. In Examples 58, 61 - 63, if the heating temperature of the suspension was too high, melamine might undergo a decomposition reaction, and the by-products generated would have an adverse effect on the properties of the modified graphene oxide and would also serve as channels for the penetration of corrosive media, reducing the corrosion resistance of the coating; if the heating temperature of the suspension was too low, the dispersibility of graphene oxide was poor and it was easy to form aggregates, thus affecting its corrosion resistance. In Example 62, the heating temperature of 90 °C was the best. In Examples 62, 64 - 65, if the proportion of quinacridone was too high, it would weaken the barrier effect of the modified graphene oxide in the coating, making it easier for corrosive media to penetrate into the interior of the coating; if the proportion of quinacridone was too low, the improvement in the corrosion resistance of the prepared waterborne paint would be limited. In Example 64, when modified graphene oxide was prepared using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide as the catalyst, with a mass ratio of graphene oxide, catalyst, and melamine of 1:0.5:2.8, a heating temperature of the suspension of 90 °C, and a ratio of quinacridone to modified graphene oxide of 1.8:9, the prepared corrosion-resistant waterborne paint had the best corrosion resistance, showing no abnormalities after being immersed in a 50 g / L sulfuric acid solution for 192 h, no abnormalities after being immersed in a 50 g / L sodium hydroxide solution for 168 h, and no phenomena of blistering, peeling, rusting, or cracking in a salt spray resistance test for 3691 h. In Comparative Example 2, unmodified graphene oxide was used, which was prone to agglomeration, resulting in phase separation, and the prepared waterborne paint had poor corrosion resistance.

[0113] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Preparation process of a corrosion-resistant water-based paint, characterized in that: The preparation process of the corrosion-resistant waterborne paint is as follows: Under stirring conditions, epoxy resin and modified waterborne polyurethane are added to deionized water and mixed evenly to obtain a slurry; the stirring speed is 450 - 550 rpm; the stirring time is 25 - 35 min; zinc phosphate particles and modified graphene oxide are added to the slurry, and stirring is continued at a speed of 300 - 350 rpm for 55 - 65 min to obtain a mixture; defoamer, thickener, dispersant and corrosion inhibitor are added to the mixture, and stirring is carried out at a speed of 500 - 600 rpm for 30 - 40 min to obtain the corrosion-resistant waterborne paint; The modified waterborne polyurethane is obtained by graphene oxide through prepolymerization reaction, chain extension reaction and neutralization reaction; the prepolymerization reaction temperature is 70 - 75 °C; the chain extension reaction temperature is 85 - 95 °C; the neutralization reaction temperature is 50 - 60 °C; The modified graphene oxide is obtained by reacting graphene oxide, catalyst and melamine in N, N-dimethylformamide; the mass ratio of graphene oxide, catalyst and melamine is 1:0.5:2.5 - 3.5; The corrosion inhibitor includes sodium oleate, aramid nanofibers and zeolite particles; the ratio of the number of parts of sodium oleate to aramid nanofibers is 1 - 5:1; the ratio of the number of parts of sodium oleate to zeolite particles is 1 - 4:1.

2.

2. The preparation process of a corrosion-resistant waterborne paint according to claim 1, characterized in that: The ratio of the number of parts of epoxy resin to modified waterborne polyurethane is 1.5 - 2.1:1.

2.

3. The preparation process of a corrosion-resistant water-based paint according to claim 1, characterized in that: The hard segment content of the modified waterborne polyurethane is 35% - 55%.

4. The preparation process of a corrosion-resistant waterborne paint according to claim 1, characterized in that: The dispersant is quinacridone; the ratio of the number of parts of quinacridone to modified graphene oxide is 1.8:7 - 12.

5. The preparation process of a corrosion-resistant waterborne paint according to claim 1, characterized in that: The preparation process of the modified waterborne polyurethane is as follows: Graphene oxide is added to deionized water and ultrasonically broken to obtain a suspension; the concentration of graphene oxide in the suspension is 1.2 - 1.8 wt%; isophorone diisocyanate and the suspension are added to a three-necked flask and stirred for 0.8 h to obtain a mixed solution one; PPG-2000 and 1.5 - 2.5 wt% stannous octoate are added to the mixed solution one to obtain a prepolymer; ethylene glycol and acetone are mixed evenly and then dropped into the prepolymer and reacted for 1.5 h to obtain a mixture two; 2,2-dimethylolpropionic acid is dissolved in N-methylpyrrolidone to obtain a mixture three; the mixture three is dropped into the mixture two to obtain a mixture four; ammonia water is added to the mixture four for the neutralization reaction, and after reacting for 20 min, it is cooled to room temperature to obtain the modified waterborne polyurethane.

6. The preparation process of a corrosion-resistant waterborne paint according to claim 1, characterized in that: The preparation process of the modified graphene oxide is as follows: Graphene oxide, catalyst and melamine are ultrasonically dispersed in N, N-dimethylformamide for 1 h to obtain a suspension; the suspension is heated to 80 - 100 °C and stirred for 10 h to obtain a brown suspension; the brown suspension is washed three times with N, N-dimethylformamide and boiling water at 100 °C, and then dried at 70 °C for 20 h to obtain the modified graphene oxide.

7. The preparation process of a corrosion-resistant waterborne paint according to claim 6, characterized in that: The catalyst is one of dicyclohexylcarbodiimide, diisopropylcarbodiimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, and N,N-di-tert-butylcarbodiimide.

8. The preparation process of a corrosion-resistant water-based paint according to claim 6, characterized in that: The graphene oxide is flaky.

9. The preparation process of a corrosion-resistant waterborne paint according to claim 1, characterized in that: The preparation process of the corrosion inhibitor is as follows: Mix 1 / 3 of the total weight portion of the sodium oleate with the aramid nanofibers in the deionized water and stir for 20 - 35 min to obtain component A; Mix the remaining 2 / 3 of the sodium oleate with the zeolite particles in the deionized water and stir for 15 - 20 h to obtain component B; Mix component A and component B to obtain the corrosion inhibitor.

10. A corrosion-resistant waterborne paint prepared by the process according to claim 1, characterized in that: The raw materials for producing the corrosion-resistant waterborne paint include epoxy resin, modified waterborne polyurethane, corrosion inhibitor, modified graphene oxide, and quinacridone.

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